The summary for Coinbase shows 3 things:
1. Total gain or loss
2. Proceeds
3. Cost basis
This is generated by importing a CSV of transactions. eg: Buy, Sell, Interest, Reward, etc.
The proceeds and cost basis are both in the ballpark of $500k, but i didn't trade an amount anywhere near that.
I fear that some sort of rounding error / floating point precision botched the calculation
